In its bungled strike against Colonel Gaddafi that reportedly killed one of his sons and three of his grandchildren, Nato has wildly exceeded its United Nations mandate. It has not only taken up the role of a protagonist in the killing of civilians, but it also appears to have become an active combatant in an undeclared and illegal war against the Libyan government. In this, Nato is now mirroring the illegality and immorality of the Libyan authorities it affects to want to interdict – and in so doing it has taken on the dirty work for a diffident United States.

And dirty, dirty work it is. Make no mistake, Nato's strategy violates international law, shows callous disregard for the innocent, and prosecutes a war approved by no international body, declared by no national parliament and sanctioned by no moral code.

The legitimate complaint against Colonel Gaddafi was his threat to annihilate his opponents in Benghazi. It was this that led to the proper initiatives of the security council and the Arab League to establish a no-fly zone and throw up a protective cordon around Benghazi – tasks that were accomplished in the first weeks following the UN vote.

Since then we have witnessed not inadvertent mission creep but egregious and knowing mission overreach. Hypocrisy is evident in the unapologetic adherence to incoherent standards in addressing Libya on the one hand, and (you name the country) Syria, Bahrain, Yemen or Saudi Arabia on the other. In all of these countries, Nato and the US have insisted on the wisdom of going slow or even backing corrupt regimes.

In Syria, where the government is also "killing its own people", prudent strategists urge restraint, cautioning that regime change can lead to unknown and pernicious consequences. With regard to Saudi Arabia, which underwrites radical madrasas in Pakistan, lends troops to quash a democratic rebellion in Bahrain and gives hundreds of millions of dollars to prestigious American and European universities, the west remains quietly complicit in all the regime does.

But it is the plain stupidity of the Nato commitment to assassination and violent regime change that is most disconcerting. What on earth is the endgame?

Like most people, I have supported interdicting civilian casualties, negotiating a ceasefire and pursuing a solution that removes Gaddafi from power while preserving the integrity of the Libyan state and the prospects for democracy. Yet is there a better way to guarantee that not one of these goals will be achieved than to try to assassinate Gaddafi? Want to be sure that he will fight to the finish at maximum cost to others? Corner him, try to kill him and his family, and warn him that he has no way out but abject surrender, certain arrest and probable execution.

But Nato is caught up in its own self-deluding rhetoric: Gaddafi is a buffoon, a weakling supported by only a few snipers and overpaid mercenaries. And a coward to boot, who can be faced down by attempts to kill him. Remember foreign secretary William Hague's absurd wishful thinking about how Gaddafi had already flown to Venezuela?

Those who will pay for Nato's hubris will be the very civilians it is supposed to protect; the rebels who will continue to face Gaddafi's wrath at the possible killing of his son and grandchildren; and perhaps innocents abroad who will now have to worry about renewed terrorism from a regime that just eight years ago voluntarily yielded its weapons of mass destruction, and became a valued ally in the war against al-Qaida. You make war personally on a head of state – as the US did in Cuba during the Kennedy era – and you reap the whirlwind.

But Nato's stupidity might just open a small window on another possibility: use the tragedy of the assassination attempt to pull back from the brink, accept Gaddafi's offer of negotiation made hours earlier, give 48 or 72 hours for a cessation of military operations so it can be realistically pursued, ask for the release of journalist Clare Gillis and her colleagues, and make clear that there are no rebel-made preconditions to negotiation. There is time, once the violence stops, to negotiate amnesty, a peaceful exit by Gaddafi perhaps overseen by the African Union, and a plan for democracy. Or is Nato really just the party of war?